CN1149361A - Global positioning system (GPS) receiver for recovery and tracking of signals modulated with P-code - Google Patents

Abstract

The invention provides a method for processing received signals in a global positioning system, which comprises the steps of: receiving LI and L2 signals transmitted from each of a plurality of satellites; independently generating replicas of the P-code pseudorandom code sequence; correlating each of the received LI and L2 signals containing the encrypted P-code sequence with the locally generated replicas of the P-code sequence; bandpass filtering each of the resultant signals from the correlating step; cross-correlating the resultant signals after bandpass filtering, to obtain a carrier signal at a frequency equivalent to (L1-L2) with a favorable signal-to-noise ratio; and controlling the step of generating the replicas of the P-code sequence.

Description

Be used to recover and follow the tracks of the GPS receiver of P code signal modulation

Invention field

The present invention relates generally to global positioning system (GPS), particularly improve the conversion speed of GPS receiver and the technology of precision.The present invention has certain contact with the U.S. Patent No. 4,972,431 that is entitled as " auxiliary P-coding GPS receiver " that belongs to R.G.Keegan on theme.Many background materials that this patent provides are also related to the present invention, for simplicity they are described too.Therefore U.S. Patent No. 4,972,431 is included in the specification as a reference.

Background technology

In the term of GPS, the present invention relates to obtain the P-coding that is subjected to suppressed carrier signal (being referred to as L1 and L2) and the technology of phase measurement, no matter whether the P code signal of modulation L1 and L2 passes through " anti-deception " encryption.As mentioned above, " coding " measures apparent distance or " pseudo-range " that refers between instrumented satellite and the receiver, and its basis is used for modulating the coding of L1 and L2 or the time of signal event is determined.

Obtain visit L1 or L2 carrier signal or visit L1 simultaneously and the L2 carrier signal has an important advantage.Compare with utilizing encoding measurement separately, carrier phase measurement has improved relatively or precision is sought in the difference location.Though then only utilize the L1 carrier signal just can finish, visit L2 and accelerated the resolution of carrier cycle ambiguity greatly and can carry out phasing to sky error.

GPS (also claiming NAVSTAR) a kind ofly determines on the earth from the signal that a plurality of orbiters receive or near the system of the customer location earth.When system finished all affixing one's name to, satellite was arranged on a plurality of orbit planes, thereby on earth or near the optional position the earth, as long as the visual field is not interrupted, will receive the signal of at least four satellites.

The track of space vehicle is accurately determined by fixing ground station and is relayed and give space vehicle.When GPS is used for navigation application, can go out on the earth or near longitude, latitude and the height above sea level of the arbitrfary point earth from the electromagnetic wave propagation Time Calculation of point more than four of space vehicle.Generally, because the amount of four the unknowns is arranged, in order to determine a position fully, ground station needs to receive four satellite-signals at least.Three unknown quantitys wherein are three-dimensional location coordinates, and they represent with longitude, latitude and height above sea level traditionally, and the 4th unknown quantity is time difference or the skew between the timer clock on timer clock and the receiver on the satellite.

The characteristics of signals of gps satellite emission can be known from document, will describe preferred embodiment of the present invention in more detail here.In brief, every satellite is with the expansion spectruming signal in two kinds of L bands of different transmit frequency, and they are called L1 and L2.Just need two kinds of signals in order to eliminate because of the transmit error that causes of ionospheric refraction.Satellite-signal is modulated by two kinds of pseudo noise codes, and a kind of C/A (coarse/careful) that is called encodes, and another kind is called P (accurately) coding, also comes modulated satellite signals by changing slower definition satellite orbit and other system information data signal.Pseudo-random code sequence is the pseudo random number on a series of certain meanings, and the pseudo random number of each pseudo random number and back does not have the relation determined, but since sequence be deterministic and the circulation of self carried out repetition, so be not real random number.

When the binary system pseudo noise code was used for the phase place of quarter-phase modulated carrier signal, the result who obtains was that a kind of spectrum density is deferred to [(sinx)/x] ²The signal that distributes, the x here is proportional with the frequency shift (FS) of relative carrier frequency.Here " spread spectrum " signal is compared with narrow band signal, its advantage be resist block or interference capability stronger.The signal of pseudo noise code modulation has useful characteristic, and promptly when the copy of signal and same pseudo noise code was correctly relevant, most of spread spectrum energy mapped on the narrow peak of frequency spectrum, still only two coherent signals synchronous in time correctly the time just like this.By the signal that receives is shut away mutually with a plurality of local pseudo-random code sequences that produce, can utilize this character to discern and the signal that separates multi-satellite.Every gps satellite adopts unique and known P coding and C/A coded sequence.Therefore, the coded sequence by the signal that receives and this locality of corresponding satellite are produced is relevant can discern specific satellite.In case the apparent launch time that identification and finish to the received signal decoding, receiver just can instrumented satellites, can calculate apparent range or pseudo-range thus.The signal definition of every satellites transmits the satellite position and constantly during certain signal, their time of reception can be measured by receiver.All measure by benchmark common time that is called the gps system time launch time.Each receiver adopts the local zone time of oneself with reference to the time of reception that writes down satellite-signal.Therefore, each receiver is all known launch time and the interior time of reception of measuring in the gps system time of measuring of local zone time.If having more than one satellite-signal at least is not the position unknown quantity, then can determine time difference and position unknown quantity between local zone time and the satellite time.For example, need the signal of four satellites in order to determine three position unknown quantitys and time difference.Near on the earth or the position of the receiver of the earth can be calculated from pseudorange data pin-point accuracy, and its precision depends on the precision of orbital data.

Use (for example marine celestial navigation) for most of civil navigations, the C/A coding can be ignored with regard to error enough and that ionospheric refraction causes.This receiver is finished evaluation work on the basis of analyzing C/A code signal (modulating on the L1 carrier signal).But for the higher difference of required precision or reconnoitre application, because the signal of two kinds of carrier frequencies can compensate the error (they are determined by carrier frequency as everyone knows) of ionospheric refraction, can determine relative position more accurately so utilize the C/A that modulates on the P coding modulated on L1 and the L2 carrier wave and the L1 carrier wave to encode.

Reconnoitre and use that to be applied in two main aspects with pure GPS navigation be different.At first preliminry basic research is compared with most of navigation application, and required precision is higher.Owing to second difference of two kinds of application, promptly most preliminry basic research only relates to the measurement of relative position between points rather than the measurement of absolute position, so can reach higher precision fortunately.In most of preliminry basic research, benchmark or reference position are highly accurate, and the relative position of other points is determined by benchmark.Straight line between benchmark and another point is sometimes referred to as baseline.

The satellite carrier signal L1 that receives by two receivers that recover the baseline two ends and at least one among the L2 are also measured the carrier phase of synchronizing time point on two positions, can obtain GPS in the best way and reconnoitre and use desired high accuracy.The wavelength of L1 carrier signal is about 19 centimetres.If the precision of phase place can determine that then the precision of range measurement can be better than 5 millimeters within 10 degree.

A difficulty that detects measuring distance according to carrier phase is to be difficult to differentiate carrier signal phase.In case after receiver was locked on the carrier signal of input, each subsequent cycles of carrier wave all was equal to, which, receiver can't be determined at a time to receive was in cycle.Reconnoitring instrument, to differentiate practical approach that carrier cycle confuses be that Position Control with instrument is in the precision of carrier cycle, promptly ± 9.5 centimetre.The position is determined to this precision two kinds of methods, promptly adopts the comprehensive Doppler measurement of geometry between abundant pseudo-range measurement or employing and the end points.First method measures average each noise of measuring by a large amount of pseudo-range (or coding).Because each P coding time slot has only 30 meters long and thermal noise each sample is only introduced several meters error (ignoring signal multi-path effect), so the P encoding measurement is feasible.But for the C/A encoding measurement, because the error that slot length is 300 meters and noise to be introduced equally also big (the multi-path effect also clearly), so the feasibility of this kind method is smaller.Measure similar based on hyperbolic navigation used in the location determining method of carrier phase measurement and the other system (for example Loran-C and Transit) for second kind.This method generates the hyperbola (every satellite one) of several the range differences definition between two positions when being orbited by same satellite.Range differences is measured by the composite carrier signal phase place of the signal between two end points that receive (comprehensive Doppler) and is determined, and end points is limited by the position of two satellites.Certainty of measurement mainly by spacing (geometry of the measurement) decision of end points, is mainly determined by the relative geometry between the satellite and measure required precision at every turn.In any situation, wherein a kind of technology has solved the phase ambiguity of the carrier signal that receives more than the utilization, and which what promptly can determine to receive is in cycle, and the phase measurement in the single cycle subsequently can reach very high precision.

The difficulty of this method need to be the long enough measurement samples of time integral of cost to eliminate the ambiguity of carrier cycle.Technology adopts difference frequency L1-L2 to reduce the certainty of measurement requirement to differentiate the carrier cycle ambiguity faster.Difference frequency or beat frequency L1-L2 are about 350MHz and wavelength is about 86 centimetres.So nearly 4.5 L1 carrier cycles of one-period of difference frequency.In fact in order to differentiate the carrier cycle ambiguity, each receiver only need be accumulated abundant sample the position is determined in 86 centimetres, rather than in 19 centimetres.For reconnoitring application, why Here it is visits the L2 gps signal is one of extremely important two reasons.If only visit L1, in order to differentiate the carrier cycle ambiguity during reprocessing, each receiver must accumulate a large amount of samples.

The other reasons of the importance of visit L2 is the ionospheric effect of compensation gps signal.Because ionosphere is different to the refraction of different frequency, thus by the phase change between two signals of observation can determine accurately ionospheric refraction to gps signal influence.L1 and L2 signal are (from the same oscillators) that is concerned with when emission.Therefore the relative phase of two carrier waves that receive provides measuring of ionospheric refraction effects, can be correspondingly the phase place of L1 be compensated.Because it is substantially the same to arrive the transmission path of two receivers, so when measuring the weak point baseline, the numerical value of ionosphere compensation is very little.But for long base line measurement, the signal pathway of reception differs bigger path, ionosphere, and needs precise results to compensate.

Can't produce the p coding to attempt " deception " system in order to ensure false transmitter, the U.S. government that is in charge of gps system has taked " anti-deception " measure.Encrypt the P coding by in the part-time of system's operation, the P coded-bit being implemented complementary operation in a certain way at least.Government can close or open encryption as required.For the system that can use at any time, the encryption P code signal of reception must be relevant with the encryption P coded sequence that this locality produces.If do not know ciphering process or can't access keys, it is impossible then adopting existing receiver technology to measure to encrypt the pseudo-range of p coding.

As previously described, the signal and the local coding that produces (P coding or C/A coding) the relevant gps signal that recovers of copy by making each input.When modulation signal was pseudorandom code sequence as P coding or C/A coding and so on, the carrier wave in the gps signal was suppressed fully.Promptly L1 of Jie Shouing or L2 signal do not comprise the radio-frequency component of L1 or L2.Yet, importantly can rebuild L1 and L2 carrier wave and measure their phase place for reconnoitring application.As long as the P coding is not encrypted, relevant by the signal that makes reception with the local P coding copy that produces (the perhaps C/A of L1 coding), be easy to recover L1 or 12 carrier waves.Adjustment on the local coding process sequential that produces is to provide relevant with the optimization of input signal.Relevant output is the single narrow-band peak that is centered close to carrier frequency.The recovery that is carrier wave is to be used for discerning and the natural result that separates the correlated process of importing gps signal.And relevant exalted carrier provides best signal to noise ratio.

Though when the P coding encrypting, can't recover L1 or L2 carrier wave, can pass through the second harmonic of the signal reinsertion of carrier phase place of square input by the P correlated process of encoding; Be that signal self multiplies each other.As everyone knows, this has the effect of all quarter-phase modulation being removed and produced in the frequency that doubles suppressed carrier the unifrequency output signal from signal.The system that adopts this technology is usually by C/A code restoration L1 carrier phase and by a square recovery L2 carrier signal, no matter whether the P of modulation coding is encrypted.Two major defects of this process are, at first square make noise also obtain square to signal, secondly square make wavelength be reduced to half effectively and also introduce the half period ambiguity.The final signal to noise ratio of recovered carrier signal is for example compared with the signal to noise ratio of the relevant reinsertion of carrier owing to a square processing degenerates, and increases more than the 30dB.

The patent of aforementioned Keegan (U.S. Patent No. 4,972,431) directly is used for improving to be recovered L1 or L2 carrier wave and obtains square technology that P coding pseudo-range is measured from the signal that is received from gps satellite, even the P code signal is through encrypting.The signal that receives shuts away mutually with the local P coded sequence copy that produces and carried out bandpass filtering before square final signal.With in bandwidth, square compare simply, the bandpass filtering before square has significantly improved signal to noise ratio.

The another kind of known technology that improves the GPS receiver performance is to make the L1 of reception relevant with the L2 signal cross to produce carrier signal of equal value at L1-L2 frequency place.Because L1 and L2 are by same P coded modulation, so this is feasible.Compare with a square technology, the remarkable advantage of crosscorrelation is to have obtained half of this value under whole 86 centimetres wavelength rather than square technology.As mentioned above, the wavelength of L1 carrier signal is about 19 centimetres, and the elimination of carrier cycle ambiguity needs the GPS position to determine in ± 9.5 cm range.If the L2 signal that square technology of utilization is recovered to encrypt, consequently the double frequency composition (2L2) under 12.2 centimetre wavelengths.Best (promptly maximum) carrier cycle ambiguity of utilizing that square technology of frequency 2L1-2L2 can obtain is provided by 43 centimetres wavelength, and required positioning accuracy is about ± and 21.5 centimetres.If but L1 and L2 signal are crosscorrelations, then final signal belongs to frequency L1-L2, and the carrier cycle ambiguity is about 86 centimetres and required positioning accuracy is about ± 43 centimetres.

For crosscorrelation L1 and L2 signal, two significant disadvantage are arranged.One is and the common square of low signal-to-noise ratio characteristic that technology is relevant.Another is that L1 and L2 signal are irrelevant usually owing to ionospheric effect.Compare with the L1 signal, the L2 signal will be subjected to the delay of varying degree in ionosphere.Owing to postpone to surpass P coding slot time, so make two received signals need the time bias of a definite form before relevant.

Compared with the prior art, the invention provides to provide and solve these difficult schemes and have the other advantage.

Summary of the invention

The present invention is conceived to a kind of method and device thereof that improves conversion speed and precision when the P coded sequence modulation that gps signal is encrypted.Although the P coded sequence is through encrypting, technology of the present invention still provides to the visit of carrier signal or to the visit of carrier difference signal.Will be understood that the term " GPS " and " global positioning system " that adopt in specification and the claims are not limited to the system that U.S. government manages, they also comprise Russian GLONASS satellite system and any similar system of developing.

In each embodiment of the present invention, eliminated the influence of P coding encrypting by square one of them carrier signal that receives or two carrier signals that receive of crosscorrelation.If be proportional to the signal of L1-L2 by the acquisition of crosscorrelation, it is higher then the complete period ambiguity of carrier phase measurement to be differentiated efficient.In those embodiment of received signal square change, produce with respect to primary carrier (square before) the half period ambiguity of phase place, and must provide the device that solves this ambiguity.In two embodiment that disclosed, differentiate the half period ambiguity so that the L1-L2 signal of polarization signal to be provided by crosscorrelation.Among embodiment, the direct crosscorrelation of L1 and L2 is arranged therein, and utilize the timing information that P coding track loop produces that separates of L1 and L2 at first to adjust the relative timing of L1 and L2 with the compensation ionospheric effect.In another embodiment, crosscorrelation is the P auxiliaring coding, and the L1 and the L2 signal that promptly offer cross correlation are produced by the auxiliary track loop of separated coding.(in preferred embodiment, the P auxiliaring coding has been made detailed description.) other aspects of the present invention and embodiment will be described in detail in the summary of the invention back.

In one embodiment of the invention, the GPS L1 that encrypts the P coding that has that receives at first encodes relevant with (unencryption) P that this locality produces with the L2 signal, relevant result's process bandpass filtering is to improve signal to noise ratio, this and aforementioned Keegan (4 in many places, 972,431) technology in the patent is identical.But in this embodiment, L1 encodes relevant and each independent process bandpass filtering with the P that this locality produces respectively with the L2 signal.The signal of filtering subsequently to produce carrier signal (L1-L2), has improved the ability of differentiating the carrier cycle ambiguity through crosscorrelation thus.

The particular step of this embodiment comprises L1 and the L2 signal that receives every satellites transmits, and this signal comprises the encrypted form of pseudo-random code sequence (being the P coding); At the copy that does not have to produce independently under the situation of encrypting P coding pseudo-random code sequence; Make that each receives to comprise the L1 that encrypts the P coded sequence relevant with the local P coded sequence copy that produces with the L2 signal obtaining two final signals, they comprise the peak value that its amplitude is represented sequential relationship between the P coded sequence of the encryption P coded sequence that receives and this locality generation; Each final signal that from correlation step, obtains of bandpass filtering; Make final signal cross relevant to obtain the carrier signal of frequency for (L1-L2) after bandpass filtering, its signal to noise ratio is also satisfactory.This method comprises that further control produces the step of P coded sequence copy so that the peak value maximum in the frequency spectrum.

In another embodiment of the present invention, the gps signal that receives at first is converted into homophase and quadrature composition, and they are relevant with the local P code signal that produces.Come from these relevant digital values subsequently in the fixed time interval integrates, the encryption period of the encryption P coded sequence that the corresponding front of this fixed time interval is determined is to provide the output sample of homophase (I) and quadrature (Q) value under the speed of corresponding encryption period.

In the change example of present embodiment, these I and Q sample produce also plural subsequently square by the signal that receives does not have square I and the Q value of the bifrequency composition of P coding encrypting effect to obtain correspondence.Bifrequency carrier wave composition can be used for controlling the generation of P coding subsequently and produce P coding pseudo-range and measure to determine the GPS receiver location.

Become in example at another of digitlization embodiment, I relevant with separately P coding and Q sample are produced and carry out crosscorrelation subsequently from the gps signal that L1 and L2 receive by said process is I with carrier wave difference composition and the Q value of L1-L2 with the generation frequency.The L1-L2 signal is convenient to differentiate the ambiguity of carrier cycle.Crosscorrelation adopts the advantage of digital technology to be since be used for controlling the integration of I and Q signal and the encryption time interval of sampling is compared, ionosphere delay is less, so do not need the signal that receives is carried out the ionospheric refraction compensation.

Particularly, the method step of numeral of the present invention square technology comprises the signal that receives the multi-satellite emission, and this signal comprises the encrypted form of pseudo-random code sequence (being the P coding); With the conversion of signals that receives is digital form; At the copy that does not have to produce independently under the situation of encrypting P coding pseudo-random code sequence, this local digital P coding that produces comprises homophase and quadrature composition; It is relevant with quadrature (Q) composition to obtain a series of relevant encryptions reception P codings and the I and the Q sample of the local P code signal that produces of unencryption with the homophase (I) of the local generation of P coded sequence copy to make the digital form of reception encrypt the P coded sequence with digital form; Be defined as encrypting the time cycle integrates I in the time interval and Q sample in front to obtain I and Q numerical value in succession; And with digital form square I and square I and the Q value of Q numerical value to obtain to have nothing to do with encryption from the integration step acquisition.

Relate to the I that the L1 that receives with the digital form crosscorrelation and L2 signal produce and the method step of Q sample and comprise L1 and the L2 signal that receives the multi-satellite emission, this signal comprises the encrypted form of pseudo-random code sequence (being the P coding); With the conversion of signals that receives is digital form; Produce the copy of the digital form not have the P coding pseudo-random code sequence encrypted independently and in this locality, the P that this this locality produces encodes and comprises homophase (I) and quadrature (Q) composition; The digital copies digital correlation that makes the reception L1 of the P coded sequence that comprises encryption and L2 signal and the local P coded sequence that produces is to obtain two final I that relate to L1 and Q signal and two other relates to final I and the Q signal of L2; The encryption time interval integrates that two pairs of final signals are formerly determined is with the I1 of the L1 signal that obtains correspondence and receive and Q1 signal I2 and the Q2 signal with the corresponding L2 signal that receives respectively; And make final [I1+jQ1] and [I2+jQ2] signal digital crosscorrelation to obtain the gratifying carrier signal of signal to noise ratio of frequency for (L1-L2).

Adopted similar digital technology to calculate the P coding tracking error of the gps signal that L1 and L2 receive according to another aspect of the present invention.The P coding front and back signal correction that the signal that particularly receives (L1 or L2) is converted into digital form and produces with this locality.Correlated results is being encrypted time interval integrates and is being used for calculating P coding tracking error subsequently.Tracking error is calculated by the vector dot product of sample of signal before and after I and the Q with I and Q sample, and I and Q signal obtain from the P coded sequence of the signal that receives and this locality generation relevant.P coding tracking error of calculating thus and common delay lock track loop logotype are with the generation of signal before and after control P coded sequence and the P coding.

Of the present invention also have an embodiment to define by the method for the signal that receives in a kind of processing global positioning system (GPS), and this method has produced frequency and has been the carrier wave difference signal through the difference of the L1 that encrypts the modulation of P code signal and L2GPS carrier signal.The method includes the steps of: receive the L1 and the L2 signal of every satellites transmits in the multi-satellite, this signal comprises the encrypted form as the pseudo-random code sequence of P coding; With the conversion of signals that receives is digital form; The independent L1 that produces unencrypted P coding pseudo-random code sequence separates digital copies with L2, and it comprises homophase (I) and quadrature (Q) composition; Produce the copy of C/A coded sequence; The L1 signal correction that makes the copy of C/A coded sequence and reception is to carry out carrier track to the L1 signal; The copy of P coded sequence is followed the tracks of with the coding that L1 and L2 signal are provided with L1 that receives and L2 signal correction respectively; Make the I1/Q1 of acquisition from relevant and the copy numeral crosscorrelation of I2/Q2 signal and P coded sequence be the gratifying carrier signal of (L1-L2) signal to noise ratio to obtain frequency; And the L1 carrier signal by (L1-L2) carrier signal that crosscorrelation is obtained and the acquisition of L1 carrier track combines and carries out carrier track L2 signal.

The present invention can also limit justice by the method for the signal that receives in a kind of processing global positioning system (GPS), this method is owing to having adopted frequency to equal the carrier wave difference signal that process is encrypted the difference of P code signal modulated carrier signal L1 and 12, so processing speed is very fast.This method may further comprise the steps: the P coding copy that produces two separation in this locality; Adopt P coding copy to follow the tracks of with the auxiliary coding that carries out L1 and L2 signal in the track loop of separating; Produce C/A coding copy in this locality; Utilize C/A coding copy to follow the tracks of the L1 carrier signal; Square L2 carrier signal is the signal of 2L2 to eliminate the influence of encrypting the P code signal and to obtain frequency, and wherein the phase place of L2 signal obtains (2L2/2) by the 2L2 phase place is divided into two; Make L1 and L2 carrier signal crosscorrelation to obtain the L1-L2 difference signal; Obtain polar signal from the L1-L2 difference signal, the ambiguity of the half period of the L2 phase measurement that is obtained by the 2L2/2 phase place can therefrom distinguish.

Particularly, in one section described method, the crosscorrelation step is a kind of direct crosscorrelation of L1 and L2 carrier signal in the above; And the step that this method further comprises is: before L1 and L2 crosscorrelation, utilize the coding track loop of separating of L1 and L2 to obtain the phase place that time sequence information is adjusted the relative L2 of L1.In another embodiment of the present invention, finish the adjustment of the relative L2 phase place of L1 by utilizing multistage phase shift register phase shift L1 with a carrier signal among the L2, thereby variable delay is provided, and along with the timing signal control lag amount of separating track loop.

Also have among the embodiment of the present invention, the crosscorrelation step is the auxiliary crosscorrelation of one of them coding, and wherein the L1 of crosscorrelation obtains from separating the coding track loop of L1 and L2 with the L2 signal.

It is evident that from the description of front the present invention has tangible progress in GPS receiver field.Particularly when the gps carrier signal was subjected to encrypting the modulation of P coded sequence, the present invention had improved precision and speed that the GPS receiver signal is handled.In Keegan patent in front, the raising of performance is inseparable with P coding encrypting " anti-deception " function under this encryption situation.

By description, will have gained some understanding to other aspects of the present invention and advantage below in conjunction with accompanying drawing.

Brief description of drawings

Fig. 1 is the simplified block diagram that is included in the sender unit in the gps satellite;

Fig. 2 is the curve chart of the spectrum density of the expansion spectruming signal of expression gps satellite emission;

Fig. 3 is the block diagram that is used for analyzing through the testing apparatus of the gps satellite signal of P coding encrypting;

Fig. 4 is the curve chart of expression filter noise response shown in Figure 3;

Fig. 5 is the output curve diagram of the shown in Figure 3 filter of expression when testing apparatus receives unencryption P code signal and make it relevant with the local P code signal that produces;

Fig. 6 is the curve chart similar to Fig. 5, but expression is filter output curve diagram when device receives encryption P code signal;

Fig. 7 is the curve chart that Fig. 5 and Fig. 6 are combined;

Fig. 8 is the simplified block diagram according to the receiver system of one aspect of the invention structure, and wherein L1 of Jie Shouing and L2 signal passed through bandpass filtering to obtain the complete wavelength of L1-L2 carrier phase difference before crosscorrelation;

Fig. 9 A and 9B have comprised the block diagram of the present invention's numeral embodiment, and the gps signal that wherein receives from carrier wave (for example L2) passes through the influence of having removed the P coding encrypting after digital square;

Figure 10 A and 10B have comprised the block diagram of another digital embodiment of the present invention, and wherein the gps signal that receives from L1 and L2 carrier wave is relevant with digital P code signal and encrypting the time cycle integrates;

Figure 11 is the signal schematic diagram how crosscorrelation influences with removal P coding encrypting that presentation graphs 10A and 10B produce;

How Figure 12 is used for producing the schematic diagram of the numeral front and back signal of L1 and L2P coding for expression and Figure 10 A digital technology similar with 10B;

How Figure 13 A and 13B are used for producing the block diagram of L1 and L2P coding tracking error signal for the front and back signal among expression Figure 12;

Figure 14 A and 14B have defined the block diagram of another preferred embodiment of the present invention jointly, and it adopts L1 and the auxiliary crosscorrelation of L2 coding.

Figure 15 A and 15B have defined the block diagram of another preferred embodiment of the present invention jointly, and the direct crosscorrelation of auxiliary quadratic sum L1 of the coding that it has adopted carrier wave to measure and L2 is to differentiate intrinsic half period ambiguity in the carrier wave measurement; And

Figure 16 A and 16B defined the block diagram of another preferred embodiment of the present invention jointly, and the auxiliary crosscorrelation of coding of auxiliary square of the coding that it has adopted carrier wave to measure (with among Figure 15 identical) and L1 and L2 is to differentiate the ambiguity of half period intrinsic in the carrier wave measurement.

The preferred mode that carries out an invention

Introduction

The present invention relates to improvement, particularly be used to reconnoitre the GPS receiver of using with high accuracy navigation (kinematics), wherein need to visit L1 and two carrier signals of L2 to improve the precision and the speed of base line measurement to global positioning system (GPS) receiver.To the visit of two kinds of carrier signals make can be correlated withization with the ionospheric refraction of compensation gps signal and be convenient to quick resolution phase ambiguity in the result who reconnoitres (kinematics).

For background technology, Fig. 1 shows L band gps signal and how to synthesize for gps satellite and launch.Transmitter on every satellite comprises the automatic clock represented with label 10 and four frequency multipliers or divider 12,14,16 and 18.Clock frequency is 10.23 megahertzes, in frequency multiplier 12, be multiplied by 154 carrier frequencies, and in multiplier 14, be multiplied by 120 so that the 2nd L to be provided the carrier frequency that band is launched 1227.6 megahertzes of (using the L2 signal indication) usefulness with 1575.4 megahertzes that L band emission (use the L1 signal indication) usefulness is provided.Transmitter also comprises the P encoder 20 and the C/A encoder 22 that produce as the another kind of pseudo noise code of C/A coding (be used for coarse/elaborated code) of generation as the pseudo noise code of P coding.

P coding is two-stage or binary coding, changes state with the speed of 10.23 megahertzes that directly come self-clock 10.Each bit or " time slot " emission in the space of coding are about 30 meters long, and the duration of coding was about for 1 week.Each complete cycle that is coded sequence is that 1 week is long.Have only 1/10th C/A code change rate (i.e. 1.023 megahertzes) of P coding to obtain by frequency divider 16 by clock 10.C/A coding be spaced apart 1023 time slots, this means after coding is through 1023 coding units and repeat.Each complete cycle of C/A coding takies 1 millisecond, and each C/A coding time slot is about 300 meters long when emission.

The divisor factor of remaining frequency divider 18 is 204600 in the transmitter, thereby produces 50 hertz clock frequency so that the memory of data 24 that comprises emission L1 and L2 signal is conducted interviews.The output of P encoder 20 and memory 24 is as the input of XOR gate 30, and the output of C/A encoder 22 and memory 24 is as the input of another XOR gate 32.The output of first XOR gate 30 links to each other with 36 with two blenders 34, and the output of second XOR gate 32 links to each other with the 3rd blender 38.The L1 carrier signal that functional block 40 is used to refer to 1575.42 megahertzes is split into the composition of two quadratures, amplifies and compound signal recombiner 42 before antenna 46 emissions by blender 34 and 38 modulation and at amplifier 44 respectively subsequently.

The L1 signal from the carrier wave of 1575.42 megahertzes, with compound P code signal of data-signal and the quadrature C/A code signal compound with same data-signal.The L2 signal from the carrier wave of 1227.6 megahertzes, with the compound P code signal of data-signal.Usually in the L1 signal, the encode power ratio of relative C/A coding of P is 1/2.

Fig. 2 shows the frequency spectrum of pseudorandomcode modulated carrier signal.Frequency is drawn along trunnion axis, and the power density of spectrum composition is drawn along the longitudinal axis.Vertical line on the spectral power density curve is by the frequency division of the repetition rate that equals to encode.The spectral line that is positioned at the distribution center place shows that carrier frequency has been subjected to inhibition.Curve be shaped as following form:

Power density=[(sinx)/x] ²

Here x is proportional to frequency f, wherein x=π f/f _Clock, and f _ClockIt is the pseudo noise code clock frequency.As seen from Figure 2, centre frequency+f _ClockWith-f _ClockThere is one-level zero point at the place in the distribution.

In common GPS receiver, before receiver location can be calculated, to finish two important function.One be measure the apparent of used relatively four satellites or for scope to determine three-dimensional position, three satellites can only be determined two-dimensional position.Another function is the data of modulating on the recovered carrier signal.For reconnoitring highly accurate base line measurement in the application, carrier signal L1 and L2 recover from the signal that receives, and carrier phase information is used for deriving the measurement of more accurate receiver relative position.Determine that from gps signal the used math equation in position is well-known and not as content of the present invention.

Each receiver all must can be distinguished each satellite.For this reason, every satellite produces the different pseudo noise code that its P encodes and C/A encodes.Receiver has many channels,, every channel comprises that the P coding that can produce the satellite coding and C/A code generator are to be used for and input signal coupling and correctly discern every satellite.

By the relevant reinsertion of carrier

Copy by producing P coding (and/or C/A coding) also makes copy and the relevant measurement that can realize pseudo-range of coding from the satellite reception subsequently.If the signal of copy and reception aligns in time, then the result of correlated process is the spike in the output signal spectrum.The central authorities that are positioned at the primary carrier frequency at spectrum peak, it is suppressed by the coded modulation in the satellite.Therefore, correlated process can be considered as to received signal " de-spread " to obtain clean carrier signal, and this signal is subjected to the modulation of the data bit of 50 slower hertz frequencies.Exalted carrier signal, particularly its phase place can be used in to be reconnoitred in the application with the relative propagation time between the receiver of accurately determining two above positions.Exalted carrier through demodulation obtaining data, these data can with the pseudo-range logotype of multi-satellite to determine the position of receiver.

The influence of P coding encrypting

Encrypting the P coding before modulated carrier makes and utilizes the P coding more difficult in the GPS receiver.Owing to encrypt, the P codes match that the encryption P coding of reception can not produce with this locality, and common GPS receiver can't lock the signal of input.Because the L2 signal only is subjected to the modulation of P coding (and data), so can't be behind the P coding encrypting by common relational approach visit L2 carrier wave.The signal that is square reception near a method of this problem replaces relevant to obtain the visit to the L2 carrier wave.When the quarter-phase modulated carrier signal self multiplies each other, consequently remove the twice carrier frequency signaling of all modulation.This can see from following trigonometric identity:

cos?2x＝1-2sin ²x

If x=2 π is f _cT, wherein f _cBe carrier frequency, then can see:

sin ²2πf _ct＝1/2(1-cos4πf _ct)＝sin ²(2πf _ct+π)

Whether no matter be bi-phase modulated, this result is the same.Therefore, square provide a kind of technology, it is no matter the quarter-phase of received signal modulation character how, can both be recovered the second harmonic of clean carrier signal.The major defect of this method is that the signal to noise ratio of final carrier signal decreases and wavelength reduces by half, thereby causes the ambiguity of half period.

Experiment basis of the present invention

Utilize remarkable improvement part of the present invention to be because the characteristic of P coding encrypting, this characteristic can be observed by the analysis of spectrum of coded signal.Thereby how Fig. 3 connects the schematic diagram of observing encryption P coding key property if showing the GPS receiver.This receiver apparatus comprises antenna 50 and coupled and be used for handling the prime amplifier 52 of L1 and L2 signal.Be experiment purpose, antenna is for pointing to the direction dish shape antenna of selected satellite.Signal is at first handled by intermediate-frequency section, and intermediate-frequency section comprises frequency mixer 54, an IF amplifier 56, second frequency mixer 58 and the 2nd IF amplifier 60.Provide the local oscillator signal that produces by frequency synthesizer circuit 62 to first and second frequency mixers 54 and 58, circuit 62 takes out frequency standard from oscillator 64.

The output of the 2nd IF amplifier 60 links to each other with correlator 66, and the P code generator 68 that produces the P coding copy that Satellite Tracking uses is taken from second input of correlator.To loop control circuit 72, its main purposes is to provide control signal so that the spectrum peak maximum in the correlator output to P code generator 68 by filter 70 in the output of correlator 66.Shown in 74, loop control circuit is auxiliary by the timing signal of the common correlated results of encoding from the C/A in the L1 gps signal.Spectralyzer 76 is encrypted the character of P code signal with observation attached to the each point of receiver test system.

Fig. 4-7 expression is from the test result of Fig. 3 device.At first, Fig. 4 has provided the noise response of filter 70.With dB is the frequency mapping of the output signal level of the unit input signal that contains broadband noise relatively.For this accompanying drawing and Fig. 5-7, the central frequency of filter is 26.593 megahertzes, and frequency scale is every lattice 200KHz, and the every lattice of the scale of output signal level are 5dB.

Fig. 5 shows the output of filter 70 when antenna 50 receives unencryption P coding and carry out P coding correlated process.The central peak of filter spectrum output is represented carrier signal.Fig. 6 shows the output of filter when the P coding encrypting.Correlated process in this case only produces and very significantly composes the peak.Fig. 7 is the synthetic of Fig. 4 and Fig. 6, and shows the characteristic [(sinx)/x] of the relevant P code signal of non-perfection ²Shape.

Encrypt two key properties of P coding as seen from Figure 7.At first, encryption is actually the additional coding of stack on the p coding; Secondly, the bandwidth of encryption is obviously narrow than p encoded bandwidth itself.Encrypt spectrum and present [(sinx)/x] ²Form, the first zero is positioned at+500KHz and-the 500KHz place.One aspect of the present invention is to utilize these characteristics to derive the L2 carrier signal that signal to noise ratio obviously improves.

Compare with unencryption P coding, the encryption P coded data that experimental session obtains has been done more detailed analysis, thereby can estimate scrambled more accurately at interval.The phase place of this analysis relates to basically encrypts the relevant of P code signal and unencryption P code signal.Final scrambled comprises change interval in time, but is easy to determine.What will further explain below is to have adopted these scrambleds also to suppose at interval by the labor to experimental data in a kind of form of the present invention and accurately determined these scrambleds at interval.

The meaning of the mathematic(al) representation of frequency item

Provided specific equation in literal and accompanying drawing, they relate to the mathematical operation to the signal of L1 and L2 frequency.The symbol of L1 and L2 item is with specific frequency representation in these equations, and promptly L2IF (intermediate frequency) is that 10.23 positive megahertz L1 IF are 10.23 negative megahertzes.The selection of IF is not basic for the present invention, can make equation be fit to any frequency by L1 and L2 item are multiplied by suitable scale constant.

The meaning that the gps signal composition is relevant

Each embodiment of the present invention has utilized the coherence of gps signal each several part.All produce and interfere mutually by the carrier signal of gps satellite emission and pseudo noise code by single oscillator and timing unit.(having the carrier phase cycle of π/4 to depart between C/A and P coding) taken place and is fixing relation generation with the phase place of relative downtrod L1 and L2 carrier signal in the encoder edge of C/A on L1 coding and L1 and P coding on the L2 simultaneously.Except the difference that the signal delay because of the ionization induction causes, the signal of reception is kept these timing relationships.

Relevant the present invention of being used to of coding and carrier wave measures so that improved GPS to be provided.Have only a phase place and coding track loop must be designed to the bandwidth of broad to hold the dynamic change of receiver oscillator.Every other track loop can narrow down following the tracks of under dynamic first loop output auxiliary subsequently.The track loop bandwidth that narrows down reduced error owing to the reason of random noise and make signal can be under the situation of much lower signal to noise ratio tracking signal.

When the P code signal descends because of the encryption quality, by adopting unencryption C/A coding, the strongest available signal also utilizes the output tracking L1 suppressed carrier phase place of this loop to go up downtrod carrier wave with coding on the auxiliary L1 of tracking and L2 subsequently, can obtain best tracking performance.L1 C/A carrier wave is tracked under the noise bandwidth with the 10-30 hertz in the second and the 3rd rank Costas loop typically, and this makes that receiver can be followed the tracks of carrier wave and not lose locking under situation about standing times over normal gravity.L1 and L2 coding and L2 carrier wave are followed the tracks of with the phase-locked loop of 1 to 0.1Hz bandwidth.

Improve

It is the signal of L1-L2 with the relevant also bandpass filtering of the local P coding that produces to produce the carrier wave difference frequency that (shown in Figure 8) according to one embodiment of present invention, the input of L1 that received before crosscorrelation and L2 signal are encrypted the P code signal.After further filtering, this signal is used to measure the frequency of all-wave appearance position and L1-L2 carrier wave difference frequency.In the patent identical or better (3dB more than) of the signal to noise ratio that bandpass filtering provided of carrying out on the 500KHz with Keegan, but owing to the all-wave that has obtained L1-L2 is long, so it is stronger to differentiate the ability of carrier cycle ambiguity.

In the second embodiment of the present invention (shown in Fig. 9 A and the 9B), the gps signal (L1 or L2) that receives is decomposed into homophase (I) and quadrature (Q) composition, the P code signal digital correlation that they produce with this locality separately, known encryption time interval integrates and subsequently numeral square to produce the second harmonic of downward conversion L1 and L2 carrier signal.Common phase-locked loop can be used for following the tracks of these quadrature signal and be used as relevant with the L1 or the L2 carrier signal of input with the phase place that θ, prediction are provided.In the distortion of present embodiment (shown in Figure 10 A and the 10B), L1 and L2 received signal are decomposed into I and Q composition separately, separately with corresponding L1 or the local P code signal digital correlation that produces of L2 and adding the close spacing upper integral individually.Digital crossover is relevant so that the long signal of all-wave at carrier wave difference frequency L1-L2 place to be provided subsequently with Q signal for the I that is drawn by these processes.When resolution improved, digital crossover is correlated with provided the relevant signal to noise ratio that equates with the corresponding simulating signal cross.But,, compensate L1 and the L2 signal ionosphere delay between receiving so need not adjunct circuit because the timing of integration and dump procedure and crosscorrelation be by the P coding control of following the tracks of separately.

The embodiment (shown in Figure 14 A and the 14B) of also having of the present invention adopts the auxiliary crosscorrelation of the coding of L1 and L2 to obtain longer L1-L2 wavelength.The coding that independent P coding track loop is used for L1 and L2 is followed the tracks of.The crosscorrelation of L1 and L2 is used to the auxiliary L2 carrier tracking loop near L1.

Also have among the embodiment (shown in Figure 15 A and the 15B) of the present invention, obtain the measurement of L2 carrier phase for plural square by the L2 signal, and differentiate the half period ambiguity of the double frequency composition of square L2 signal by the direct crosscorrelation of L1 and L2.The phase polarity of L1-L2, promptly the phase place of the relative L2 of L1 that obtains from direct crosscorrelation is used to differentiate square ambiguity of the half period of L2 signal.

Of the present invention also have an embodiment (Figure 16 A is with shown in the 16B) similar with the 15B illustrated embodiment to Figure 15 A, except L1 and L2 crosscorrelation P coding are assisted.Present embodiment is the same with the embodiment of Figure 14 A, 14B, 15A and 15B, has utilized by the relevant strong L1 carrier signal that derives of C/A coding, and wherein the C/A encoding phase can be derived from L1P encodes track loop or C/A coding track loop.

The crosscorrelation of the L1 of band pre-filtering and L2P coding

Fig. 8 has described one aspect of the present invention, and wherein gps signal L1 and L2 are received respectively by circuit 80 and 82, conversion down in intermediate frequency mixer 84 and 86 subsequently.Be used for relevant in the final signal input correlator 88 and 90 with P code signal from this locality generation of P code generator 92.1 and 92.2.Correlator 88 and 90 output are handled by band pass filter 94 and 96 respectively, import cross correlation 98 subsequently.If the relative delay that causes because of ionospheric refraction between L1 and the L2 signal is compared less with the inverse of filter bandwidht, then the output of cross correlation 98 comprises the composition of L1-L2, because the wavelength after square is 86 centimetres rather than 43 centimetres, so the resolution capability of carrier phase ambiguities is improved.The output of cross correlation 98 is handled to obtain the L1-L2 carrier phase measurement by loop filter 99 and L1-L2 carrier track control logic 100.

Being used to import correlator 88 controlled by two identical P coding track loop with the generation that 90 pause P code signal pauses.For the L1 signal, P coding track loop comprises P encoder 92.1, correlator 101.1, another 500KHz filter 102.1, squaring circuit 103.1, loop filter 104.1 and loop control circuit 105.1.The output of IF frequency mixer 84 is emitted to correlator 101.1 together with the shake P code signal on the circuit 106.1 from P encoder 92.1.The processing of 500KHz filter 102.1, squaring circuit 103.1, loop filter 104.1 and loop control circuit 105.1 is passed through in the output of correlator 101.1, and is used for controlling the sequential of P encoder 92.1.P encoder 92.1 is also exported the pause P code signal of delivering to correlator 90 on circuit 107.1.Adopt identical P coding track loop for the L2 signal, it comprises P encoder 92.2, correlator 101.2, another 500KHz filter 102.2, squaring circuit 103.2, loop filter 104.2 and loop control circuit 105.2.

The circuit of Fig. 8 is similar to the part of prior art, and wherein L1 and L2 received signal are obtained the L1-L2 carrier signal of carrier phase in phase-locked loop with acquisition through crosscorrelation.The novel part of this embodiment of the invention is relevant with P coding and increased by two band pass filters 94 and 96, and their optimum wideband is approximately 500kHz, and this is definite by the observation to the character of the encryption P code signal of gps satellite.

In adding close spacing, carry out the numeral square of L2 signal

Fig. 9 A and 9B have described the digital form of the present invention that is used for square the signal of being derived by L2 signal that receives and the local P code signal that produces.Omitted for simplicity under the frequency and changed, but it should be understood that down that change-over circuit needs.The L2 signal receives on antenna 110, is handled by band pass filter 112, and is digital form in analog to digital converter 114 internal conversions.The latter can adopt the form of hard limiter circuit, and its output provides one digital resolution, perhaps can adopt multi-stage quantization.The local P code signal that produces also adopts digital form (+1), and the sine and the cosine value at the carrier phase angle of estimating together with the IF signal input in multiplier 116 and 118.The phase angle θ that estimates is used to calculate (perhaps searching) corresponding sin θ and cos θ, imports multiplier 116 and 118 subsequently.Final long-pending be transfused to multiplier 120 and 122, and as the input of analog to digital converter 114.Two integrations and unloading circuit 124 and 126 are delivered in multiplier 120 and 122 output respectively.The latter equals coded signal integration period at interval by the control of the timing signal on the circuit 128 to provide.Fixed time interval is by to encrypting the analysis of P coding, particularly the analysis of the correlated results of encrypting P code signal and unencryption P code signal determined.

These are the homophase and the quadrature composition of the L2 signal that receives by signals of integration and unloading circuit output on circuit 130 and 132 periodically.They are input to plural squaring circuit 134, produce the composition of quadrature signal, use I respectively _SQAnd Q _SQExpression.These compositions input to common phase-locked loop circuit and recover to carry out carrier wave, as 136 places represent.

Plural square root in the squaring circuit 134 according to following formula finish input signal from multiplication:

(I+jQ) ²＝(I ²-Q ²)+j2IQ＝I _SQ+Q _SQ

I _SQAnd Q _SQUse by common phase locked track loop, produced estimation carrier phase angle θ used among Fig. 9 A.

Numeral with the received signal that adds the close spacing integrates square obtained same result with and bandpass filtering relevant at the P coding after square corresponding analog signal, promptly signal to noise ratio obtained tangible improvement and time of differentiating carrier wave monocycle ambiguity still less.

L1 is relevant with the digital crossover of L2 signal in adding close spacing

For the L1 that receives and the crosscorrelation of L2 analog signal, this technology belongs to simulation, but has a significant advantage.Figure 10 A and 10B show required circuit.Because what many parts were finished is the identical functions shown in Fig. 9 A, so adopt identical label and represent L1 or L2 circuit with suffix " .1 " or " .2 ".Shown in Fig. 9 A, for simplicity, conversion is omitted under the frequency, but conversion is essential under the common frequency.The circuit that produces digital signal I1 and Q1 from L1 and L1P code signal is shown in Figure 10 A.It comprises band pass filter 112.1 that the P modulation signals is passed through, analog to digital converter 114.1 multipliers 116.1,118.1,120.1 and 122.1 and integration unloading circuit 124.1 and 126.1.I1 and Q1 signal are exported on circuit 130.1 and 132.1 by integration unloading circuit 124.1 and 126.1.Carrier phase angle θ L1 as described in Fig. 9 A from numeral square acquisition.

Equally, the circuit of generation digital signal I2 and Q2 is shown in Figure 10 B from L2 and L2P code signal.It comprises band pass filter 112.2 that the P modulation signals is passed through, analog to digital converter 114.2 multipliers 116.2,118.2,120.2 and 122.2 and integration unloading circuit 124.2 and 126.2.I2 and Q2 signal are exported on circuit 130.2 and 132.2 by integration unloading circuit 124.2 and 126.2.Carrier phase angle θ L2 as described in Fig. 9 A from numeral square acquisition.

From output signal I1, Q1, I2 and the Q2 input digit cross correlation 134 ' (Figure 11) of the circuit of Figure 10 A and 10B, it produces output I and the Q signal relevant with difference on the frequency L1-L2.These use the common phase-locked loop of signal input of I (L1-L2) and Q (L1-L2) expression in the drawings, with 136 ' expression.Digital crossover correlator 134 ' is finished relevant according to following formula:

(I1+jQ1)(I2-jQ2)＝(I1I2+Q1Q2)+j(Q1l2-I1Q2)＝I _(L1-L2)+jQ _(L1-L2)

I _L1-L2And Q _L1-L2Be used for the phase place of estimating carrier frequency difference L1-L2 by phase locked track loop etc.

This digital crossover of L1 and L2 signal is relevant to have the relevant the same advantage of analog crossover with signal, promptly because difference on the frequency L1-L2 has replaced 2L1-2L2, so the time of resolution monocycle phase ambiguity significantly reduce.Compare with common crosscorrelation, signal to noise ratio has improved 13dB.Another advantage of digital method is the difference ionosphere delay that need not to compensate the relative L1 of L2.At this moment the integration unloading circuit produces the output (500KHz speed) that is spaced apart 2 microseconds because most ionosphere delay has only 0.3 microsecond.Therefore, be easy to interrelated and can not incur loss because of postponing from the corresponding L1 of integration unloading circuit and L2 output, and the variable time delay circuit there is no need fully.

The digital processing of P coding tracking error

Figure 12 represents how to adopt and signal before and after Fig. 9 A, the 10A circuit similar with 10B produces numeral.Circuit comprises multiplier 116.1 ', 118.1 ', 120.1 ' and 122.1 ' and integration unloading circuit 124.1 ' and 126.1 '.Multiplier 116.1 ' and 118.1 ' has the sine and the cosine input of the numerical value of estimating phase angle and L1 PE/L signal respectively.Signal and value 0 before and after the P coding of Here it is L1 carrier wave ,+1 or-1.L1 is multiply by in multiplier 116.1 ' and 118.1 ' output in multiplier 120.1 ' and 122.1 ', the output of back multiplier adds up in integration unloading circuit 124.1 ' and 126.1 '.Finally go up with the final signal of encrypting output constantly and represent with IEL1 and QEL1 at circuit 130.1 ' and 132.1 '.The same circuit of representing with square 140 produces corresponding signal from the L2 signal that receives, these signals are represented with IEL2 and QEL2.

As shown in FIG. 13A, fall into a trap at vector dot product circuit 142.1 and calculated L1 P coding tracking error.This tracking error is used for producing the PEL signal of L1 subsequently by the normal elements of loop filter 144.1, digital phase shifter or voltage-controlled oscillator 146.1 and P code generator 148.1 and so on.Vector dot product circuit 142.1 compute vectors I1+Q1 and IEL1+jQEL1 are long-pending.The dot product of vector is the cosine that the product of vector size is multiplied by the angle of vector.The vector dot product of two vectors is provided by following formula:

I ₁I _EL1+Q ₁Q _EL1

Figure 13 B has described the PEL signal that the circuit identical with Figure 13 A still is used to calculate L2.In this case, P coding tracking error is calculated as I2IEL2+Q2QEL2.The P coding tracking signal that L1 and L2 derive among Figure 13 A and the 13B is used for the timing that L1P coding and L2P are encoded among control chart 10A and the 10B.

The timing of L1P coding and L2P coding among P coding tracking error control chart 9A, 10A and the 10B.Under encryption rate, adopt P coding tracking error signal to compare in the same way and improved 6dB with the tau dither technique.This method need not to understand encryption technology, encrypts regularly as long as be determined by experiment.Measure with higher precision and the multi-path effect that reduced from the final P coding pseudo-range of L1 and L2 and to obtain.

Adopt another embodiment of the auxiliary crosscorrelation of coding

Figure 14 A and 14B show the main receiver function of the embodiments of the invention of the coding auxiliary figure crosscorrelation that adopts L1 and L2 signal.In these accompanying drawings, adopted new label, but similar in many parts and the earlier figures.

In Figure 14 A, 14B, 15A, 15B, 16A and 16B, adopt digital form to finish processing.In Figure 14 A, suppose L1 signal conversion under overfrequency, filtering and digitlization before two frequency mixers 160 of input of reception.Therefore I and the Q signal composition shown in frequency mixer 160 is output as on the circuit 164.The signal correction in the C/A encoder 166 in the autocorrelator 168 is come in the I of these L1 and Q signal composition territory, and encoder 166 provides I and Q signal to export in the adder circuit 172 on circuit 170.The latter finishes with integration unloading circuit identical functions noted earlier and with 1 millisecond interval integration I and Q signal.

The output of adder circuit 172 provides the signal of expression L1 carrier wave.During these common Costas loop errors that input to dashed lines 174 expressions calculate.All parts that dot can be realized with software in microprocessor.The Costas loop error calculates 174 and provides feedback signal to carrier wave numerically-controlled oscillator (NCO) 176, and its produces the output that frequency is 308dl, the reception L1 signal (comprising in the receiver reference oscillator because any frequency shifting that inexactness causes) that Doppler effect produces.Well-known is that the GPSL band signal has comprised the radio-frequency component that produces because of the kinetic Doppler frequency shift of the relative receiver of launching an artificial satellite.For the L1 signal, the frequency of reception is 308F+308dl, and F is the fundamental frequency (F=5.115MHz) of other GPS frequency of generation here, and 308dl is the frequency that Doppler effect causes.After changing down in an embodiment of the present invention, the frequency that is applied to the L1 signal on the frequency mixer 160 is-2F+308dl.Certainly, conversion factor also falls within the scope of the invention under other.

Provide the basic sample frequency of 8F to the circuit 178 at receiver, thereby it one is divided into four and produces the 2F frequencies in frequency divider 180.Signal recombiner 82 is with basic 2F sampled signal and to combine to produce frequency from the 308dl signal of carrier wave NCO176 be the signal of 2F+308dl, and it is used for driving sin/cos tracing table 162, closes the L1 carrier tracking loop in receiver effectively.

The part of the clock signal of C/A encoder 166 derives from the 8F sample frequency on the circuit 178.The 8F signal is that the Doppler frequency of 8dl is compound with scale in another composite module, carries out scale by the 308dl signal to carrier wave NCO176 output and can obtain this Doppler signal.Particularly, the output of carrier wave NCO176 by frequency multiplier 186 and frequency divider 188 scales to 8dl, this multiplier 186 be multiplied by the frequency of 4 times of factors and frequency divider with frequency divided by 154.The output of recombiner 184 is further cut apart obtaining the clock frequency of 2F+2dl by the factor 4 in another frequency divider 190, thereby drives P encoder 192.Clock frequency is cut apart the clock signal that drives C/A encoder 166 to produce by the factor in the frequency divider 194 10.

The signal that utilizes P encoder 192 to provide, particularly front and back signal and halted signals (they are applied to two correlators 196 and 198 respectively together with I on the circuit 164 and Q signal) realize that the coding of L1 signal is followed the tracks of.The output IEL of correlator 196 and QEL input summing circuit 200, this summing circuit 200 is at these signals of time interval upper integral of corresponding scrambled (w coding).Equally, the output IP of correlator 198 and QP input summing circuit 202, this summing circuit 202 is being encrypted these signals of time interval upper integral.Summing circuit 200 inputs to the vector dot product circuit 204 of realization vector dot product calculating (identical with mode shown in Figure 13 A) with 202 output, and produces the encoding error signal as output.With 1 millisecond time interval integration, its output offers common loop error and calculates 208 the encoding error signal in summing circuit 206.The latter provides control signal to one of them frequency divider, and particularly dispenser 188, and this dispenser deletion and adding are proportional to the clock pulse of encoding error signal, thereby the coding of closing receiver is followed the tracks of.

The coding track loop of the L2 signal that receives and the L1 signal similar of reception are except the parts of L2 add ('), the label of Figure 14 B all is identical.Therefore, sine and the cosine signal that provides by blender 160 ' and sin/cos tracing table 162 ' is I and Q composition with the L2 signal decomposition that receives.I is relevant with front and back P code signal with pause in correlator 196 ' and 198 ' with the Q composition, and relevant result by summing circuit 200 ' and 202 ' in the w encoded interval to the correlated results integration.Integral result is handled producing the encoding error signal by vector dot product circuit 204 ', this signal in summing circuit 206 ' with 1 millisecond interval integration.Loop error calculates the control signal that 208 ' feedback adjusting is applied to the clock signal on the P encoder 192 '.

The carrier track of L2 realizes by crosscorrelation circuit 210, and this circuit has output and the summing circuit 202 ' of summing circuit 202 on circuit 212 and goes up the L2I of output and Q signal as input at circuit 212 '.The I of crosscorrelation circuit 210 and Q output respectively by I1I2-Q1Q2 and-(I1Q2+I2Q1) provide.These outputs in summing circuit 214 with 1 millisecond interval integration.The final common phase-locked loop Error Calculation 216 of L1-L2 signal input, the L1 Costa loop error that it also receives from auxiliary operation calculates 174 L1 signal.The reason that adopts auxiliary phase-locked loop is that the signal to noise ratio of the L1 signal of deriving with " non-square " C/A coding is compared, and the signal of the signal of square reception or two receptions of crosscorrelation can cause relatively poor signal to noise ratio.Because L1 and L2 signal are concerned with basically, except ionospheric effect, any frequency error that in the L1 signal that receives, measures can scale to produce the frequency error of equal value of L2 signal.The auxiliary operation of phase-locked loop utilizes the advantage of this relation.The frequency scaling that receives from the L1 signal is to L2 and be used for realizing adopting the bandwidth of the crosscorrelation that does not have auxiliary phase-locked loop narrower to the bandwidth ratio of following the tracks of the L2 carrier wave.

Particularly phase-locked loop Error Calculation 216 produces the error signal that is applied on the carrier wave NCO176 ', and the output of carrier wave NCO176 ' is that frequency is the Doppler frequency signal of 240d2.This acts on frequency multiplexed device 182 ', and this frequency multiplexed device is the standard 2F frequency signal on the receiving lines 218 also.The output of recombiner 182 ' is applied to sine-cosine tracing table 162 ' and goes up to close carrier tracking loop.In a word, this embodiment of the present invention adopts the C/A coding to follow the tracks of the L1 carrier signal and adopts P coding auxiliaring coding to follow the tracks of L1 and L2.(the coding tracking on the L1 can be encoded by P, and auxiliaring coding is followed the tracks of or the C/A coding is followed the tracks of) L2 carrier track is realized adjusting L2 carrier signal NCO with the acquisition control signal by the crosscorrelation of L1 and L2.

Adopt the additional embodiments of direct crosscorrelation

Figure 15 A and 15B show the further modification that system of the present invention is done, and wherein L2 carrier track and phase measurement square are finished by the plural number of L2 signal, and the direct crosscorrelation of L1 and L2 is used for differentiating the carrier wave ambiguity of the half period in measuring.The coding of L1 and L2 signal is followed the tracks of identical with embodiment among Figure 14 A and the 14B with the mode of finishing of L1 carrier track.

Particularly, follow the tracks of relevant receiver section with L1 and L2 coding and the receiver section relevant with the L1 carrier track has the parts identical with 14B with Figure 14 A, identical parts adopt identical label in Figure 15 A and 15B.Figure 15 A part different with 14B with 15B and Figure 14 A described now.

Finished the L2 carrier track by from add close spacing summing circuit 202 ', deriving pause I and Q output and these outputs being applied to plural squaring circuit 220.The function that this circuit is realized is (I+jQ) ², i.e. I ²-Q ²+ j2IQ.The result of plural number square is imported another summing circuit 222, and this circuit is at 1 millisecond time interval upper integral I and Q signal.The output input of summing circuit 222 calculates 224 to the auxiliary phase-locked loop error of L2 carrier wave NCO176 ' feedback control signal.The same with the auxiliary phase-locked loop error calculating 216 of Figure 14 B, the advantage that the L1 that the auxiliary phase-locked loop error calculating 224 of Figure 15 B utilizes the C/A coding to derive measure the high s/n ratio of being correlated with has realized that also the tracking bandwidth of L2 measurement is narrower than additive method.

Shown in Figure 15 B, the required parts of half period ambiguity of differentiating the L2 carrier wave comprise the shift register 230 that is used for the L1 signal, two additional summing circuits 232 and 234, crosscorrelation circuit 236, another summing circuit 238 and polarity detectors 240.It is the clock frequency of 8F that shift register 230 receives from L1 signal on the circuit 164 and circuit 178 upper frequencies.L1 signal delay amount is determined at circuit 239 and the 239 ' timing signal that upward receives by P encoder 166 and 166 ' respectively in the shift register 230.These timing signals are called the X1A epoch of P encoder, and the ionosphere delay of the relative L1 signal of difference expression L2 signal between them.Shown in Figure 15 B, shift register is 16 rank.At the clock frequency place of 40MHz, every rank are equivalent to the time delays of 25 nanoseconds and can the superpose delay of 0.4 microsecond of whole register, and this is enough to compensate maximum ionosphere delay.Therefore, shift register has compensated the difference ionosphere delay between L1 and the L2 effectively and has produced next synthetic L1 and the L2 signal of the variable interval upper integral that is limited at P coding polarity transition by summing circuit 232 and 234 effectively.(this technology advantage of having utilized P coding polarity transition can not betide each P coding time slot has improved the signal to noise ratio of the crosscorrelation of 3dB.) import the L2 signal of summing circuit 234 by L2I and the 164 ' derivation of Q circuit.The L1 of integration is relevant in circuit 236 subsequently with the L2 signal, and relevant result in summing circuit 238 with 1 millisecond interval integration.Polarity detector 240 provides the binary signal that is used for differentiating intrinsic half period ambiguity in the L2 phase measurement, and this will be discussed in more detail below.

In a word, the embodiment shown in Figure 15 A and the 15B adopts the plural number of L2 signal square to carry out phase measurement, has utilized the higher signal to noise ratio that obtains than direct crosscorrelation.Then, in order to differentiate in the L2 phase measurement and adopt direct crosscorrelation with respect to the half period ambiguity of L1 Measurement Phase.

Polarity detector

Similar parts provide the method that makes things convenient for of differentiating half period ambiguity in the common quadrature signal among Figure 15 B Semi-polarity detector 240 and Figure 16 B.The output of polarity detector 240 has the phase place of 0 degree or 180 degree and adds the input signal that is applied on the carrier wave NCO176 '.The carrier wave that carries out simultaneously on L1 and the L2 channel is measured.What measure on the L1 channel is the phase place of L1.If allow to encode auxiliary square (to remove cipher round results), what then measure on the L2 channel is the phase place of double frequency carrier wave (2L2).Because required amount is the phase place of L2 carrier wave, so the latter's measurement must be divided into two.Therefore, the scope of final L2 carrier wave measurement has only the 0-180 degree.That is the ambiguity of, having only the half period.By two phase measurements (L1 phase place and 2L2/2 phase place) and the output of polarity detector are compared, can derive the correct half period of 2L2/2 phase place, at this moment because polarity detector provides the measurement to relative phase between L1 and the L2.Therefore, though the measurement of L2 channel square the L2 signal also can be reported as holocyclic resolution.

Only in detecting, polarity adopt the output of cross correlation 210 directly having tangible advantage in auxiliary crosscorrelation (Figure 16 A and 16B are discussed below) two methods of crosscorrelation (Figure 15 A and 15B) and P coding.In direct crosscorrelation, the noise of the phase place of measuring from the auxiliary square channel of P coding is starkly lower than the noise of crosscorrelation channel.In the auxiliary crosscorrelation of P coding, the low 3dB of noise that measures in the auxiliary crosscorrelation channel of noise ratio P coding of the phase place of from the auxiliary square channel of P coding, measuring.

Adopt other embodiment of the auxiliary crosscorrelation of coding:

Figure 16 A and 16B show the further improvement to system of the present invention.Shown in the embodiment of Figure 15 A and 15B, L2 carrier track and phase measurement square are finished by the plural number of L2 signal, and the auxiliary crosscorrelation of the coding of L1 and L2 is used for differentiating the carrier wave ambiguity of the half period in measuring.The coding of L1 and L2 signal is followed the tracks of identical with embodiment among Figure 14 A and the 14B with the mode of finishing of L1 carrier track.

Particularly, follow the tracks of relevant receiver section with L1 and L2 coding and the receiver section relevant with the L1 carrier track has the parts identical with 14B with Figure 14 A, identical parts adopt identical label in Figure 16 A and 16B.

Finished the L2 carrier track by from add close spacing summing circuit 202 ', deriving pause I and Q output and these outputs being applied to plural squaring circuit 220.The function that this circuit is realized is (I+jQ) ², i.e. I ²-Q ²+ j2IQ.The result of plural number square is imported another summing circuit 222, and this circuit is at 1 millisecond time interval upper integral I and Q signal.The output input of summing circuit 222 calculates 224 to the auxiliary phase-locked loop error of L2 carrier wave NCO176 ' feedback control signal

Shown in Figure 16 B, differentiate the identical of the required parts of the half period ambiguity of L2 carrier wave and Figure 14 B, i.e. cross correlation 210, summing circuit 214 and polarity detector 240.Cross correlation 210 receives the auxiliary L1 of P coding and L2 input and summing circuit 214 produces (L1-L2) output signal that is used for polarity detector 240.Polarity detector provides determines (L2) ²The phase information of carrier wave polarity promptly can be differentiated the half period ambiguity of square carrier signal.

In a word, the embodiment shown in Figure 16 A and the 16B adopts the plural number of L2 signal square to carry out phase measurement, has utilized the higher signal to noise ratio that obtains than direct crosscorrelation.Then, adopt the auxiliary crosscorrelation of coding for the cycle ambiguity of differentiating in the L2 phase measurement.

Conclusion

Can see that by aforementioned the present invention has represented the major progress of GPS receiver technical field.With aforesaid U.S. Patent No.4,972,431 situation is the same, and the benefit that the technology that specification disclosed makes all GPS users obtain from recover the L2 carrier signal phase is that the performance of encryption P code signal before the emission is better.

As in prior art, technology of the present invention is not walked around the P coding encrypting.The purpose of encrypting is the measure of " anti-deception ".One of problem that those are in charge of GPS mechanism major concern is that some people can produce the false signal with correct signal same format, because they are risen in other places and comprise other misdatas, this signal will be cheated military user, give the positional information of their mistakes.The encryption of P code signal has prevented this unauthorized behavior effectively.The invention provides a kind of technology, make the non-military user of system satisfied but can not encrypted the influence of " anti-deception " L1 and L2 signal.The present invention allows the passive user of system to realize the improved equipment performance of reconnoitring when allowing the P coding encrypting, but the present invention can't be decrypted and be helpless to the false signal that anyone seeks generation to the P code signal.

For fear of unnecessary complexity, in specification, omitted the general feature of GPS receiver.For example, as described above described in the patent when P coding unencryption, need the parallel receiver path.And, need a plurality of L1/L2 receiver channels to handle the signal of while, as described in the patent of front from multi-satellite.

Compared with the prior art the present invention has a plurality of advantages.Particularly embodiment relates to is that the P coding adopts the encryption rate band pass filter after relevant in the receiver of optimizing linear mode crosscorrelation L1 and L2 signal, so has improved signal to noise ratio.The digital embodiment of some announcements adopts relevant and digital square of the digital crossover that adds L1 and L2 signal under the close spacing, and provides above the superiority of simulating the quadratic sum crosscorrelation.

Though the present invention can do various modifications, change, scope of the present invention is limited by the back claims.

Claims (26)

1. the method for a signal of handling to receive in the global positioning system, its generated frequency equal the carrier wave difference signal through the difference of L1 that encrypts the modulation of P code signal and L2 carrier signal, it is characterized in that comprising following steps:

Receive the L1 and the L2 signal of each emission in the multi-satellite, this signal comprises the encrypted form of the pseudo-random code sequence that is called the P coding;

Produce the copy of unencrypted P coding pseudo-random code sequence independently;

Make the L1 that comprises each reception of encrypting the P coded sequence relevant with the L2 signal to obtain to have two final signals of the frequency spectrum of the peak value of timing relationship between the P coded sequence that comprises encryption P coded sequence that expression receives and this locality generation with the local P coded sequence copy that produces;

Each final signal from correlation step is carried out bandpass filtering;

After bandpass filtering, final signal is carried out crosscorrelation to obtain the final signal that frequency equals (L1-L2) and has better signal to noise ratio; And

The step that produces P coded sequence copy is controlled so that the peak value maximum of frequency spectrum.

2. the method for claim 1 is characterized in that the copy of controlling the generation of P coded sequence copy comprises the timing information that obtains expression satellite pseudo-range.

3. the method for claim 1, the step that it is characterized in that bandpass filtering correlation step result are to be ± f in bandwidth _NullCarry out in/2 the frequency spectrum, here ± f _NullDefined the position at the interior one-level of frequency spectrum zero point.

4. the method for claim 1, the step that it is characterized in that bandpass filtering correlation step result are to carry out in the bandwidth between 10 megahertzes and 25 kilo hertzs.

5. the method for claim 1, the step that it is characterized in that bandpass filtering correlation step result are to carry out in the bandwidth about 500 kilo hertzs.

6. derive the device of (L1-L2) carrier signal for the reinforcement precision of in global positioning system (GPS) receiver, using, it is characterized in that comprising:

Reception antenna is used for receiving the GPS L1 and the L2 signal of each emission of multi-satellite, and this signal comprises the encrypted form as the pseudo-random code sequence of P coding;

Two P code generators are used for producing independently the copy of unencrypted P coding pseudo-random code sequence;

Two correlator circuits are used to make the L1 that comprises each reception of encrypting the P coded sequence relevant with the local P coded sequence copy that produces with the L2 signal;

Two band pass filters are used for each final signal from interlock circuit is carried out bandpass filtering;

The cross correlation circuit is used for signal relevant and process filtering is carried out crosscorrelation to obtain the final signal that frequency equals (L1-L2) and has better signal to noise ratio.

7. device as claimed in claim 6 is characterized in that further comprising:

Circuit is used to produce the sequential of P coding timing controling signal with the P code generator of adjustment L1 and L2.

8. method of handling the signal that receives in the global positioning system (GPS), its recovers to it is characterized in that comprising following steps through encrypting the L2 carrier signal of P code signal modulation:

Receive the signal of each emission in the multi-satellite, this signal comprises the encrypted form of the pseudo-random code sequence that is called the P coding;

With the conversion of signals that receives is digital form;

Produce the copy of unencrypted P coding pseudo-random code sequence independently, copy comprises homophase and quadrature composition;

Make the encryption P coded sequence of the digital form that receives relevant with quadrature (Q) composition to obtain a series of I and the Q sample of associated encryption and unencryption P code signal with the homophase (I) of the local P coded sequence copy that produces;

In front by encrypting time cycle integrates I that the time cycle determines and Q sample to obtain I and Q value in succession; And

Digital square of I and I and the Q value of Q numerical value that obtains by integration step to obtain to have nothing to do with encryption.

9. method as claimed in claim 8 is characterized in that further comprising following steps:

The encoding error signal produces the step of P coded sequence copy before and after adopting with control.

10. for the device that is used to derive the L2 carrier signal of strengthening precision that in global positioning system (GPS) receiver, uses, it is characterized in that comprising:

Reception antenna is used for receiving the gps signal of each emission of multi-satellite, and this signal comprises the encrypted form of the pseudo-random code sequence that is called the P coding;

Analog to digital converter, the conversion of signals that is used for all receptions is a digital form;

Numeral P code generator is used for producing independently the encode digital copies of pseudorandom code sequence of the P that comprises homophase (I) and quadrature (Q) composition;

The digital correlator circuit is used to make the encryption P coded sequence of reception relevant with quadrature (Q) composition with the homophase (I) of the local P coded sequence copy that produces;

Two integrations and unloading circuit, the encryption interlude that is used for the encryption P code signal determined in corresponding front at interval in the I in succession and the Q numerical value of generation; And

The numeral squaring circuit is used for square coherent signal by in succession I and Q numeric representation to obtain the higher L2 carrier signal of signal to noise ratio.

11. device as claimed in claim 10 is characterized in that further comprising:

Digital signal processing circuit comprises the vector dot product circuit, thereby is used for producing control signal to adjust the maximum signal that also obtains every satellite pseudo-range of expression of output that digital P coding maker regularly makes the L2 carrier signal.

12. the method for a signal of handling to receive in the global positioning system, its generated frequency equal the carrier wave difference signal through the difference of L1 that encrypts the modulation of P code signal and L2 carrier signal, it is characterized in that comprising following steps:

Receive the L1 and the L2 signal of each emission in the multi-satellite, this signal comprises the encrypted form of the pseudo-random code sequence that is called the P coding;

With the conversion of signals that receives is digital form;

Produce the digital copies of separating of unencrypted P coding pseudo-random code sequence L1 and L2 independently, copy comprises homophase (I) and quadrature (Q) composition;

Make the L1 that encrypts the P coded sequence comprising of reception relevant with the Q composition with the I of the local P coded sequence copy that produces to obtain two final I relevant and Q signal and two final I and Q signals relevant with L2 with L1 with the L2 signal;

Encrypting in the time interval two pairs of final signals of integration respectively with the I1 that obtains the corresponding L1 signal that receives and 12 and Q2 signal of Q1 signal and the corresponding L2 signal that receives;

Final I1/Q1 is carried out the relevant final signal that equals (L1-L2) and have better signal to noise ratio with the acquisition frequency of digital crossover with the 12/Q2 signal; And

Control figure produces the step of P coded sequence copy to keep synchronous with the P coded sequence that receives.

13. a device of handling the signal that receives in the global positioning system (GPS), its generated frequency equal the carrier wave difference signal through the difference of L1 that encrypts the modulation of P code signal and L2 carrier signal, it is characterized in that comprising:

Antenna assembly is used for receiving the L1 and the L2 signal of each emission of multi-satellite, and this signal comprises the encrypted form of the pseudo-random code sequence that is called the P coding;

The conversion of signals that is used for receiving is the device of digital form;

Be used for producing independently the device of the digital copies of separating of unencrypted P coding pseudo-random code sequence L1 and L2, copy comprises homophase (I) and quadrature (Q) composition;

Be used to make the L1 and I with the Q composition relevant device of L2 signal that encrypt the P coded sequence comprising of reception, thereby obtain two final Is relevant and Q signal and two final I and Q signals relevant with L2 with L1 with the local P coded sequence copy that produces;

Be used for encrypting in the time interval the device of two pairs of final signals of integration respectively with 12 and Q2 signal of the I1 that obtains the corresponding L1 signal that receives and Q1 signal and the corresponding L2 signal that receives;

It is relevant to obtain the device that frequency equals (L1-L2) and has the final signal of better signal to noise ratio that final I1/Q1 and 12/Q2 signal are carried out digital crossover; And

Be used for the control figure formula and produce the step of P coded sequence copy to keep and the synchronous device of P coded sequence that receives.

14. a method that detects and compensate the tracking error in global positioning system (GPS) the P code signal that receives is characterized in that comprising following steps:

Receive the signal of each emission in the multi-satellite, this signal comprises the encrypted form of the pseudo-random code sequence that is called the P coding;

With the conversion of signals that receives is digital form;

By the relevant digital carrier signal that comprises composition I and Q of deriving of signal that makes reception with the local P coded sequence that produces;

Produce digital P coding front and back signal, the relative timing of the P code signal that its expression receives, and comprise homophase and quadrature composition;

Make the homophase of signal before and after the encryption P coded sequence of the digital form that receives and the digital P coding and quadrature composition digital correlation from the result of digital correlation, to obtain a series of homophases and quadrature samples;

Be defined as encrypting the time interval integrates homophase in the time interval and quadrature samples in front to obtain (I before and after the I in succession _EL) and Q front and back (Q _EL) numerical value;

Numerical calculation is by I _ELAnd QI _ELThe vector dot product of the carrier signal of signal and I and Q definition is to obtain P coding tracking error signal before and after the P coding of definition; And

Control produces the step of P coding front and back signal so that P coding tracking error is zero.

15. method as claimed in claim 14 is characterized in that the step of compute vectors dot product comprises amount of calculation (I.I _EL+ Q.Q _EL).

16. method as claimed in claim 14 is characterized in that finishing each step with respect to the L1 gps signal that receives; And

Described method further comprises a series of same steps of finishing with respect to the L2 gps signal that receives.

17. be used for detecting and compensating the device of tracking error of the global positioning system (GPS) of reception, it is characterized in that comprising:

Antenna assembly is used for receiving the signal of each emission of multi-satellite, and this signal comprises the encrypted form of the pseudo-random code sequence that is called the P coding;

The conversion of signals that is used for receiving is the device of digital form;

Be used for the relevant device of deriving the digital carrier signal that comprises composition I and Q of signal with the local P coded sequence that produces by making reception;

Be used to produce the device of digital P coding front and back signal, the relative timing of the P code signal that described signal indication receives;

Being used for signal decomposition before and after the digital P coding is the device of homophase and quadrature composition;

Be used for making the homophase of signal before and after the encryption P coded sequence of the digital form that receives and the digital P coding and quadrature composition digital correlation to obtain the device of a series of homophase and quadrature samples from the result of digital correlation;

Be used for being defined as in front encrypting the time interval integrates homophase in the time interval and quadrature samples to obtain (I before and after the I in succession _EL) and Q front and back (Q _EL) device of numerical value;

Be used for numerical calculation by I _ELAnd QI _ELThe vector dot product of the carrier signal of signal and I and Q definition is to obtain the device of P coding tracking error signal before and after the P coding of definition; And

Be used to control the step that produces P coding front and back signal so that P coding tracking error is zero device.

18. the method for the tracking error of a global positioning system (GPS) that is used for detecting and compensating reception is characterized in that comprising following steps:

Receive the signal of each emission in the multi-satellite, this signal comprises pseudo-random code sequence and the another kind of encrypted form that is called the pseudo-random code sequence of C/A coding that is called the P coding;

By the relevant digital carrier signal that comprises composition I and Q of deriving of signal that makes reception with the local C/A coded sequence that produces;

Adopt carrier tracking loop to follow the tracks of carrier signal, thereby when adopting the C/A coding of carrier track, improved carrier signal to noise ratio; And

Timing by P coding track loop control C/A coding.

19. the method for a signal of handling to receive in the global positioning system, its generated frequency equal the carrier wave difference signal through the difference of L1 that encrypts the modulation of P code signal and L2 carrier signal, it is characterized in that comprising following steps:

Receive the L1 and the L2 signal of each emission in the multi-satellite, this signal comprises the encrypted form of the pseudo-random code sequence that is called the P coding;

With the conversion of signals that receives is digital form;

Produce the digital copies that the L1 of unencrypted P coding pseudorandom code sequence separates with L2 independently, it comprises homophase (I) and quadrature (Q) composition;

Produce the copy of C/A coded sequence;

The L1 signal correction that makes the copy of C/A coded sequence and reception is so that carrier track L1 signal;

The copy of P coded sequence is followed the tracks of with the coding that L1 and L2 signal are provided with L1 that receives and L2 signal correction respectively;

Make that be (L1-L2) and have carrier signal than high s/n ratio from the copy numeral crosscorrelation of the relevant I1/Q1 that obtains and 12/Q2 signal and P coded sequence to obtain frequency; And

By (L1-L2) carrier signal that will take from the crosscorrelation step and the L1 carrier signal combination of taking from the L1 carrier track L2 signal is carried out carrier track.

20. the method for a signal of handling to receive in the global positioning system, its generated frequency equal the carrier wave difference signal through the difference of L1 that encrypts the modulation of P code signal and L2 carrier signal, it is characterized in that comprising following steps:

Receive the L1 and the L2 signal of each emission in the multi-satellite, this signal comprises the encrypted form of the pseudo-random code sequence that is called the P coding;

With the conversion of signals that receives is digital form;

Produce the digital copies that the L1 of unencrypted P coding pseudo-random code sequence separates with L2 independently, it comprises homophase (I) and quadrature (Q) composition;

Produce the copy of C/A coded sequence;

The L1 signal correction that makes the copy of C/A coded sequence and reception is so that carrier track L1 signal;

The copy that makes the P coded sequence respectively with the L1 that receives and L2 signal correction so that the carrier track of L1 and L2 signal to be provided;

Numeral square relevant L2 signal is to provide signal to noise ratio higher relatively L2 phase measurement; And

Make relevant L1 and L2 signal digital crosscorrelation to differentiate by the half period ambiguity in the L2 phase measurement of numeral square acquisition.

21. the method for a signal of handling to receive in the global positioning system owing to adopted frequency to equal carrier wave difference signal through the difference of the L1 that encrypts the modulation of P code signal and L2 carrier signal, so improved processing speed, is characterized in that comprising following steps:

The local P coding copy that produces two separation;

Adopt P coding copy to come the coding of auxiliary respectively L1 and L2 signal to follow the tracks of;

The local C/A coding copy that produces;

Adopt C/A coding copy to follow the tracks of the L1 carrier signal;

Crosscorrelation L1 and L2 signal are higher than the signal to noise ratio that is respectively applied for one of two carrier waves differentiating the complete period ambiguity to obtain signal to noise ratio; And

Adopt (L1-L2) signal to follow the tracks of the L2 carrier signal.

22. the method for a signal of handling to receive in the global positioning system owing to adopted frequency to equal carrier wave difference signal through the difference of the L1 that encrypts the modulation of P code signal and L2 carrier signal, so improved processing speed, is characterized in that comprising following steps:

The local P coding copy that produces two separation;

Adopt P coding copy to assist the L1 in the track loop of separating and the coding of L2 signal to follow the tracks of;

The local C/A coding copy that produces;

Adopt C/A coding copy to follow the tracks of the L1 carrier signal;

Square L2 carrier signal is the signal of 2L2 to eliminate the influence of encrypting the P code signal and to obtain frequency, and wherein the phase place of L2 signal is by the acquisition that is divided into two of 2L2 phase place;

Crosscorrelation L1 and L2 carrier signal are to obtain the L1-L2 difference signal;

Derive polar signal from the L1-L2 difference signal, can determine the half period ambiguity of L2 phase measurement thus.

23. method as claimed in claim 22 is characterized in that:

The crosscorrelation step is the direct crosscorrelation of one of them L1 and L2 carrier signal; And

Described method further is included in L1 and adopts the step of adjusting the phase place of the relative L2 of L1 from the timing information that separates the derivation of coding track loop of L1 and L2 before with the L2 crosscorrelation.

24. method as claimed in claim 23 is characterized in that by one in displacement L1 and the L2 carrier signal in multistage shift register to provide variable delay and the control lag amount under the timing signal of track loop of separating is finished the step of the relative L2 phase place of adjustment L1.

25. method as claimed in claim 22 is characterized in that the crosscorrelation step is the auxiliary crosscorrelation of one of them coding, wherein the L1 of crosscorrelation and L2 signal are derived by the separated coding track loop of L1 and L2.

26. the method for the tracking error of a global positioning system (GPS) that is used for detecting and compensating reception is characterized in that comprising following steps:

Receive the L1 and the L2 signal of each emission in the multi-satellite, this signal comprises the pseudo-random code sequence that is called the P coding, and it may be an encrypted form, and the another kind of pseudo-random code sequence that is called the C/A coding, and its sequential and P encode relevant;

The digital carrier signal that comprises composition I and Q by signal that makes reception and the relevant derivation of C/A coded sequence that local C/A code generator provides;

Employing comprises the carrier signal that the carrier tracking loop of local C/A code generator is followed the tracks of reception, thereby provides the carrier signal that is higher than the signal to noise ratio when adopting the P coding to carry out carrier track when adopting the C/A coding of carrier track;

Follow the tracks of the P coded sequence of reception with the carrier tracking loop that comprises local P code generator, thereby so when adopting the P coding, provide better coding to follow the tracks of because the P coded sequence changes faster and precision encoding is higher; And

Under signal, control the timing of the C/A coding of C/A code generator from P coding track loop.

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